For the crumb topping, combine white sugar, brown sugar, cinnamon, and flour. Stir in the melted butter and mix until the crumbs are the size of a pea. Set aside.

Mashed bananas.

The batter.

For the muffin, whisk together flour, baking soda, baking powder and salt in a bowl. In another bowl, mix together sugar, mashed bananas, melted butter, vanilla extract and egg. Combine the dry ingredients to the wet ingredients and stir just to combine. Do not over mix.

Pour batter into the muffin liners using your 1/4 measuring cup and sprinkle the top of the muffins with the crumb topping. Bake 18-20 min.